The present invention relates to an inverter device and more particularly to an inverter device having the redundancy of a function, i.e. multiple safety function, which shutdowns a drive signal of a semiconductor switching element.
European Norm “EN954-1” (ISO13849-1) is known as the basic safety standard of a mechanical device. With the European Norm “EN954-1”, as shown in Table 1, safety requirement items demanded of a mechanical device and system behavior corresponding to that requirement items are classified by category.
For example, category “3” of Table 1 stipulates, in addition to the requirement of category “1”, that a design should be such as to provide redundancy in order that a safety function is not impaired due to a single failure.
TABLE 1CategoryRequirements (in brief)System BehaviorBSafety related parts ofWhen a fault occurs, it canmachine control systemslead to a loss of the safetyand/or their protectivefunction.equipment, as well as theircomponents, shall bedesigned, constructed,selected, assembled andcombined in accordance withrelevant standards so thatthey can withstand theexpected influence. Basicsafety principles shall beapplied.1The requirements ofAs described in categorycategory B apply togetherB but with higher safetywith the use of wellrelated reliability of thetried safety componentssafety related function.and safety principles.(The higher the reliability,the lesser the likelihoodof a fault).2The requirements of categoryThe loss of safety function isB and the use of well trieddetected by the check. Thesafety principles apply. Theoccurrence of a fault can leadsafety function(s) shall beto the loss of safety functionchecked at machine start-upbetween the checkingand periodically by theintervals.machine control system. If afault is detected, a safe stateshall be initiated or if thisis not possible, a warningshall be given.3The requirements of categoryWhen the single fault occurs,B and the use of well triedthe safety function is alwayssafety principles apply. Theperformed. Some but not allsystem shall be designed sofaults will be detected. Anthat a single fault in any ofaccumulation of undetectedits parts does not lead tofaults can lead to the loss ofthe loss of safety function.safety function.Where practicable, a singlefault shall be detected.4The requirements of categoryWhen the. faults occur, theB and the use of well triedsafety function is alwayssafety principles apply. Theperformed. The faults will besystem shall be designed sodetected in time to prevent thethat a single fault in any ofloss of safety functions.its parts does not lead tothe loss of safety function.The single fault is detectedat or before the next demandon the safety function. Ifthis detection is not possible,then an accumulation of faultsshall not lead to a loss ofsafety function.
A heretofore known technology of an inverter device redundantly designed in order to comply with the category “3” is shown in FIGS. 4 to 6.
In a first heretofore known technology shown in FIG. 4, 100A is an inverter device, and 200 is a motor acting as a load. The inverter device 100A includes a control block 110A and a drive block (power source block) 120A.
A CPU 111, which generates IGBT gate signals, and a first shutdown circuit 112 disposed on the control block 110A, a second shutdown circuit 121, a drive photocoupler 122, and an IGBT bridge circuit 123 are disposed on the drive block 120A. The IGBT bridge circuit 123 with a three-phase bridge circuit formed of six bridge-connected IGBTs, the output terminals of the three phases are connected to the motor 200.
In the heretofore described configuration, normally, the gate signals generated by the CPU 111 pass through the first shutdown circuit 112 and are inputted into the drive photocoupler 122, and by the IGBTs of the IGBT bridge circuit 123 driven by output signals of the drive photocoupler 122, an alternating current voltage is applied to the motor 200. By this means, the motor 200 rotates.
Also, in the event that the need arises to stop the motor 200 due to an abnormality, a failure, or the like occurring, a shutdown signal from the exterior is inputted into the first and second shutdown circuits 112 and 121. Herein, as the shutdown signal, there is an output signal of a light curtain which optically detects that someone has approached a manufacturing line in which the motor 200 is installed, and the like.
As the gate signals and primary side power source of the drive photocoupler 122 are shutdown by the first and second shutdown circuits 112 and 121 operating in response to the shutdown signal, the motor 200 is reliably stopped.
By making the gate signal shutdown function redundant using the duplicate shutdown circuits 112 and 121 in this way, the safety of the system is maintained.
Furthermore, in a second heretofore known technology shown in FIG. 5, 100B is an inverter device and 200 is a motor, as previously described. The inverter device 100B includes a control block 110B and a drive block 120B.
A CPU 111, which generates IGBT gate signals, and first and second shutdown circuits 112 and 113 disposed on the control block 110B, a drive photocoupler 122 and an IGBT bridge circuit 123 are disposed on the drive block 120B.
In the heretofore described configuration, normally, the gate signals generated by the CPU 111 pass through the first and second shutdown circuits 112 and 113, and are inputted into the drive photocoupler 122, and by the IGBTs of the IGBT bridge circuit 123 driven by output signals of the drive photocoupler 122, an alternating current voltage is applied to the motor 200. By this means, the motor 200 rotates.
Also, when a shutdown signal from the exterior is inputted into the first and second shutdown circuits 112 and 113 on the control block 110B, the gate signals are shutdown by the first and second shutdown circuits 112 and 113 operating in response to the shutdown signal, meaning that the motor 200 is reliably stopped.
Also, even with this heretofore known technology, by making the gate signal shutdown function redundant by using the duplicate shutdown circuits 112 and 113 on the control block 110B, the safety of the system is maintained.
Furthermore, FIG. 6, which shows a third heretofore known technology, is the circuit illustrated in IEC61800-5-2, Annex B, FIG. B.3.
In FIG. 6, 100C is an inverter device, 120C is a drive block, 122 is a drive photocoupler, 122X is an upper arm photocoupler, 122Y is a lower arm photocoupler, and 123 is an IGBT bridge circuit.
Numeral 130, being a control block into which a shutdown signal a is inputted, includes a CPU 131, a first shutdown circuit 132, a memory 133, a clock generating circuit 134, and a photocoupler 122X power source shutdown transistor 135. 140, being a shutdown block into which a shutdown signal b is inputted, includes a second shutdown circuit 141, a watchdog timer 142, and a photocoupler 122Y power source shutdown transistor 143. Also, 136 is a shutdown confirmation circuit.
In the heretofore described configuration, normally, gate signals generated by the CPU 131 are inputted into the drive photocoupler 122, and by the upper and lower arm IGBTs of the IGBT bridge circuit 123 being driven by output signals of the drive photocoupler 122, an alternating current voltage is applied to the motor 200. By this means, the motor 200 rotates.
When the shutdown signal a from the exterior is inputted into the first shutdown circuit 132 in the control block 130, the power source of the upper arm photocoupler 122X is shutdown by a shutdown command a′ sent to the CPU 131, and the CPU 131 turns off the transistor 135. Also, when the shutdown signal b from the exterior is inputted into the second shutdown circuit 141 in the shutdown block 140, the power source of the lower arm photocoupler 122Y is shutdown by the transistor 143 being directly turned off by a shutdown command b′.
The configuration is such that, when the shutdown commands a′ and b′ are input into the CPU 131, the IGBT gate signals themselves are also shutdown.
Furthermore, actuation signals of the transistors 135 and 143 are fed back to the CPU 131, and at a time of the shutdown operation, the CPU 131 issues a command, and a shutdown confirmation signal is output from the shutdown confirmation circuit 136.
According to this heretofore known technology, as the power source of the drive photocoupler 122 and the IGBT gate signals are shutdown, the motor 200 is reliably stopped.
In JP-A-09-238476 (Paragraphs [0011] to [0023], FIG. 1, and the like), a technology is disclosed wherein, in an abnormality detection and protection circuit of semiconductor elements which configure a power bridge circuit, as well as various kinds of abnormality (a load short circuit, an overcurrent flowing to the semiconductor elements, or a drop in a control power source voltage) being detected by category, stored, and the switching of the semiconductor elements being stopped, the abnormalities are reported to an integrated control system.
With the first and third heretofore known technologies, a passing of a shutdown signal from the control block 110A to the drive block 120A, or from the control block 130 and shutdown block 140 to the drive block 120C, is necessary. For this reason, the number of pins of a connector for carrying out the passing of the shutdown signal increases, and the circuit becomes complicated. Also, with the first heretofore known technology, it is necessary to mount the shutdown circuit 121 on the drive block 120A, and the drive block 120A increases in size.
With the second heretofore known technology, as the two shutdown circuits 112 and 113 are mounted on the control block 110B, the configuration of the shutdown circuits is complete within the control block 110B, thus, it is possible to simplify the circuit configuration of the drive block 120B.
However, in the event that, for example, the IGBT bridge circuit 123 has three phases, six gate signals are generated by the CPU 111 and, as the gate signals have to be input into and output from the shutdown circuits 112 and 113, the wiring becomes complicated. Also, there is a problem in that the mounting area of the shutdown circuits on the control block 110B increases, and the block as a whole increases in size.
With the heretofore known technology described in JP-A-09-238476 (Paragraphs [0011] to [0023], FIG. 1, and the like), as the number of abnormality detection circuits, abnormality storage circuits, and the like, needs to coincide with the number of varieties of abnormality, there is a problem in that this leads to more complicated and larger circuit configuration.
Therein, an object of the invention is to enable a simplification of a circuit configuration, and a miniaturization of the circuit as a whole, in an inverter device wherein a shutdown function is made redundant in order to satisfy the safety standards of the European Norm “EN954-1”, and the like.
Further objects and advantages of the invention will be apparent from the following description of the invention.